fix: remove required from entities' id

also adds "Global" entity for storing global configuration

Entities/Image.cs

@@ -1,8 +1,9 @@
 namespace Shadow.Entities;
 public class Image
 {
-	required public int Id { get; set; }
+	public int Id { get; set; }
 	required public string Uri { get; set; }
+	required public string Filetype { get; set; }
 	public int State { get; set; }
 	public int? SongId { get; set; } = null;